ive a c15 one but its worn and could probably do with a rebore . altrnatively, if you have a barrel thats on max oversize for bsa pistons, you can bore them further to take the piston out of a t100 triumph which is higher compression and about 265cc and gives a useful power increase.

Thanks to Looper and johnr - apologies for the late reply. I just got back from holiday to find I'm not getting notifications of replies - I'll check my group settings. I've managed to get a cylinder now, but with a cracked liner, so now I'm looking for tips on changing the liner without causing any damage... Thanks again - John.